mm: hugetlb: remove minimum_order variable

commit 641844f5 ("mm/hugetlb: introduce minimum hugepage order") fixed
a static checker warning and introduced a global variable minimum_order to
fix the warning.  However, the local variable in
dissolve_free_huge_pages() can be initialized to
huge_page_order(&default_hstate) to fix the warning.

So remove minimum_order to simplify the code.

Link: https://lkml.kernel.org/r/20220616033846.96937-1-songmuchun@bytedance.comSigned-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/hugetlb.c

@@ -66,12 +66,6 @@ static bool hugetlb_cma_page(struct page *page, unsigned int order)
 #endif
 static unsigned long hugetlb_cma_size __initdata;
 
-/*
- * Minimum page order among possible hugepage sizes, set to a proper value
- * at boot time.
- */
-static unsigned int minimum_order __read_mostly = UINT_MAX;
-
 __initdata LIST_HEAD(huge_boot_pages);
 
 /* for command line parsing */
@@ -2152,11 +2146,17 @@ int dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn)
 	unsigned long pfn;
 	struct page *page;
 	int rc = 0;
+	unsigned int order;
+	struct hstate *h;
 
 	if (!hugepages_supported())
 		return rc;
 
-	for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << minimum_order) {
+	order = huge_page_order(&default_hstate);
+	for_each_hstate(h)
+		order = min(order, huge_page_order(h));
+
+	for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << order) {
 		page = pfn_to_page(pfn);
 		rc = dissolve_free_huge_page(page);
 		if (rc)
@@ -3148,9 +3148,6 @@ static void __init hugetlb_init_hstates(void)
 	struct hstate *h, *h2;
 
 	for_each_hstate(h) {
-		if (minimum_order > huge_page_order(h))
-			minimum_order = huge_page_order(h);
-
 		/* oversize hugepages were init'ed in early boot */
 		if (!hstate_is_gigantic(h))
 			hugetlb_hstate_alloc_pages(h);
@@ -3175,7 +3172,6 @@ static void __init hugetlb_init_hstates(void)
 				h->demote_order = h2->order;
 		}
 	}
-	VM_BUG_ON(minimum_order == UINT_MAX);
 }
 
 static void __init report_hugepages(void)